François-Nicolas-Benoît Haxo was born in Lunéville, France and began his career with the Military engineers (Génie Militaire) in 1793. Haxo embraced the military early in his career. He finished the School of Artillery and Engineers of Chalons-sur-Marne in 1793 with the rank of Lieutenant Minor. Soon after, Haxo earned the rank of Captain of Engineers in the Army of the Rhine in 1794. In 1796, he attended École Polytechnique. In 1801, he became a battalion commander following the capitulation of Fort Bard (1 June 1800) by the Army of Italy, part of the French military in 1792 - 1802.